1000000030

120

t\Viee its weight of ho! water; evaporate and erynallirc

as liefore. Repeat the Came opemion!illl he liquor wi l!

yield no more cryllals: it wil! then be very thick, and

gryes by the name of

tilo/ha

n¡/r~.

Earehs and 1I0nes that ha"e been impregnaten wilh a·

nimal or vegetable juiees fufceptible of putrcfaaion, and

ha"e beenlong cxpofed tOthe air, but !hdtered from Ihe

fun and rain, are thofe \Vhieh yicld the grcm lf qnaotilYof

oitre. BUI al! fOTls of carths aod 1I00es are not eqnally

lit to produce il. None is ever fou od in Hinls or fands

of a eryllallioe nature.

Sorne eanhs and 1I0nes abound

with nilre, thal it ef–

/lorefees (pontaoeouOy on lheir furface, in Ihe form of a

crylblline down. This nitre may be eolleaed with

brooms, and aeeordingly has Ihe name of

Jnl/·p(lr~

! '

lJ.wP¡

IIEt.

Some of Ihis fon is brough l from India.

The proee(s by whieh our falt.pme makers extraft

nitre in quanlities, out of rubbi!h aod nilrous earths, is

very nearly the fame with Ihat here fet do\Vn: (o Ihat we

!hall oot enter in10 a particular ae(ount of it. Wc !hall

only lake nOlice of one Ihing, whieh it is of fome eoofe ·

'luence to koow ; oamel)', that Ihere is 00 nil.rons eanh

\Vhieh does oot eontaio (ea·fall alfo. Tlwgreatdl quao·

lities of Ihis fall are to be IOllod id'·tho(e earths whieh

have been drenehed wilh urine or olher animal excre–

ments . Now, as Ihe rubbilh of old Iloufes in greal ci–

ties is io Ihis clafs, it comes 10 pafs, that when Ihe fa lt·

pelre workers evaporale a nilrous lixiviulIl drawo from

Ihat rubbifh, as foon as the evaporalion is brought 10 a

cenain piteh, a great nnny lillle eryllals of fea·falt

form in Ihe liquor, and fal! 10 Ihe bonom of lhe "ellel.

The ralt-pme workers in Franee cal! Ihefe f.line par–

lides

/h.

grail.,

and take great care 10 feparnte them

from lhe liquor, (whieh as long as il cominues hot keeps

tlle ( It-pelre difl'olvcd) before they fet il 10 eryllallife.

'I'his faa feems a linl. Gogular, eonGdering thal t'ea·f.1lt

dirYol'es in waler more eaGly than falt-petre, and ery–

ílallifes with more diffieulty.

lo order to difeover Ihe caule of this phenomenoo, we

mull reeollea, ftrll, Ihat water eao kcep but a deler.

minatequantity of any falt in folulion, and Ihat if waler

fully faluwed wilh a (alt be evaporaled, a quaotily uf

fal¡ will er)'l!allife in proponion tO lhe quaolity of Waler

el'aporalcd. Seeondly, thal lhofe falts whieh are the

mall foluble in warer, panielllarly thofe whieh run in

the air, will difl'olve in eold afld in boiling waler equal.

Iy; wherca, mueh ¡¡remr quanlilies of Ihe orher fAIIs

will difl'olve in hot and boiling waler lhan in eold water.

T hefe Ihings 'being admitted, when we know that fea–

fall is one of ¡he Grll fort, and fal¡.pelre of lhe fceond,

the reafon why fea- falt preeipitatcs in Ihe prcparalion of

[ah·pme appears at once. For,

When the folulion

off.lt'

petreand fea fall comes tObe

evaporaled 10 fueh a degree that il eootains as mueh fea

falt asil poOibly eao, Ihis falt mull begin

eryllalhfe, aod

conlinue

do (o gradually as Ihe

evap~ration

advanees.

Hut

beeauf~

al Ihe fame lime it does nOl contain as mueh

falt· pelreas it eanhold, fccing il is eapable ofdifl'olving a

mueh gmtcr quaolity thereof when it is boiling hOI

Iha~

wheo it is cold, this lan named fal t wi!! not cryllallife

fo foon.

the evaporillioo \Vere coolinued till Ihe caCe

Ihe falt·petre came 10 be the fame with that of th!

fea falt, lhen the fah-petre alfo would begin 10 eryllallife

gradually in proponion tO the water evaporated, and the

, wo falts would canlinue cryllalliGng promi(euollny toge–

ther : but il is never carried (o far

nor is it ever necefl'ary;

for as Ihe water eools it beeomes more and more ioea–

pable of holdingiD folutionthe fame quantity of falt-petre

as wheo it wa's boiling hoto

And. lhen comes the very reverfe, wilh regaíd to the

eryllallrGog of Ihe IWO falts

for Ihen the falt.pelre

OIOOtS, and not Ihe fea-falt. The reafon of Ihis faa al·

fo is founded 00what has jull heen faid. The fea·falt,

of whieh cold water will difl'olve as much as boiliog wa–

ter, and whieh owed its cryllallifiog before only to lhe

evaporalinn, now ceafes to crynallife as fooo as Ihe eva-o

poration eeafes

while the falt.petre, whieh the water

kept difl'olved ooly beeaufe il was boiling hot, is foreed'

to eryllalliCe merely by the cooling of Ihe watér.

Wheo ¡he (olulion of

falt~ petre

has yielded as many

cryllals of lhal falt as it eaoyield by eoollOg. it is again

evaroraled, aod being then fuf!'ered to eool yields more

cryllals And Ihus Ihey continue evaporating and cry-

1I.lIiGng lill the liqllor will afford no more eryllals.

is plain, that as lhe fah'pme er)'lIallifes, the pro–

portioo of fca·falt 10 lhe difl'olving liquor inereafes; and

as a eenain quantilYof waler evapomes alfo during

the lime emrloyed in eryllalliGng Ihe falt·petre, a quao–

tityof

(~a·f.h,

proponioned tO the water· lo evaporaling,

mul! cryllallife in that time: and this is Ihe reafon why

falt1lclre is aduherated wilh a plixture of fea·falt.

hkewife foilows, thal Ihe lall cryllals of oitre, ob¡ained

froma folulion of fall petre and fea-fah , coolain mueh

more fea·f.1It than the ¡irll.

rrolO afl Ihat has been faid coneeroing Ihe eryllallifa'–

tion of fah-petre and lea

·f.ll,

it is eafy to deduce the

proper way of purifying ¡he lormer of th& two falts

from a mixlore of the laner. Fur Ihis purporc the falt–

pelre

be refioed need only be dlil'oll'ed in fa ir water.

T he proponion helwten the tWO (¡!lIS in Ihis fceond fo–

Imion is I'rry difr.rent fromwha! il was in the former;

for il eoritains no more fea·falt Ihan whal had eryllal–

lired

al~ng

with lhe fah -pme under fal'ollr of the evapo–

ration, Ihe rcll having been left difl'oll'ed io the liq'uor

Ihal rcfufed 10 yicld aoy more nitrous eryllals.

As there is lherefore a mueh gremr quantity of fah–

pelre Ihan 'of fea-fall in this feeond

folu~ion,

il is eafy

cvapome il to fueh a degree Iha! a grea, deal of fah–

pelre nlall eryllallife, whilt much more of Ihe water

mull neeefl'arily be evaporaled before any of the fea· fal:

\ViII erylLdlife.

However, Ihe falt.petre is nOl yet eOlirelyfreed from

all mixture of fea-fah by lhis fidl purifiealioo; for lhe

the cr)'lIals obtained from this liquor, io whieh fea-falt

is dilfolved, are lIill rnerulled, aod, as it were, iofcaed

therewith: henee it comes, Ihat, 10 refine Ihe fah·petre

thoroughly, Ihefe cryUaififalions mull be repeated four.

or Gvc limes.

Thc f,lt-pelre meo commonly cooleot Ihemfel'es wilh

cryllalfiGng it lhriee, and eall Ihe product fah-petre of

the firn, fceond. or third nlOOI, aecording 10 Ihe nllm–

ber of cryllallifations it

ha~

uodergone. Ilut lheir be!!

refined